The idea
A compound area can be found by splitting the shape into familiar non-overlapping parts.
Follow these steps
- Choose rectangles or triangles that cover the whole shape without overlap.
- Find each part's area.
- Add the parts, or subtract a cut-out from a larger enclosing shape.
rectangle area = length × width
See the method in action
Example 1
The combined area of two equal-area rectangles is 34 cm². What is the area of each rectangle?
Not drawn to scale
- Use the labelled areas: 34 ÷ 2 = 17 cm².
Example 2
The complete outer rectangle has area 130 m². The L-shape shown has area 114 m². What is the area of the missing rectangular corner?
Not drawn to scale
- Subtract the remaining area from the complete rectangle: 130 − 114 = 16 m².
A useful shortcut
Add the parts, or subtract a cut-out from a larger enclosing shape.
Watch out for these
Three fresh questions
Ready to check the method? You will get three fresh, validated questions.